|Publication number||US6812842 B2|
|Application number||US 10/027,675|
|Publication date||2 Nov 2004|
|Filing date||20 Dec 2001|
|Priority date||20 Dec 2001|
|Also published as||CA2465847A1, DE60209820T2, EP1455673A2, EP1455673B1, US20030122653, WO2003053270A2, WO2003053270A3|
|Publication number||027675, 10027675, US 6812842 B2, US 6812842B2, US-B2-6812842, US6812842 B2, US6812842B2|
|Inventors||Steven C. Dimmer|
|Original Assignee||Calypso Medical Technologies, Inc.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (105), Non-Patent Citations (2), Referenced by (113), Classifications (18), Legal Events (8)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This invention relates to systems for activating miniature markers, and more particularly to systems for excitation of resonating miniature marker assemblies for use in locating the markers in three-dimensional space.
Systems have been developed to activate and detect remote activatable marker assemblies positioned, as an example, in or on a selected item or object. The markers generate a signal used to detect the presence of the marker. Many of the activatable markers are hard-wired to a power source or other equipment external from the object. Other systems have been developed that utilize resonating leadless markers, also referred to as wireless active markers, positionable at or near a selected target. These wireless active markers are typically activated or energized by a remote excitation source that generates a strong continuous excitation signal. Accordingly, the markers generate a detectable marker signal that must be distinguished from the strong continuous excitation signal and then analyzed in an effort to try to accurately determine the target's location. The process of distinguishing a weak marker signal from the strong continuous excitation signal, while maintaining sufficient accuracy for determining the marker's location, has proven to be very difficult.
Other systems have provided detection of leadless markers to determine a two-dimensional proximity (e.g., X, Y coordinates) to detectors for use with game boards, surgical tag detection devices, and medical tube placement verification systems. In the case of the game boards, a unique game piece with a resonator of a predetermined frequency is moved across the game board, and the X and Y location ordinates of the game piece relative to the game board are displayed so the players can determine the general location of the game piece on the game board. U.S. Pat. No. 5,853,327 to Gilboa identifies that the X, Y coordinates, as a function of amplitude or phase, may be determined experimentally for a given game board design. Additionally, Z distance away from the game board may be determined to a sufficient accuracy for game use by the strength of the signal above the game board provided that the signal is not a strong function of the X and Y locations. U.S. Pat. No. 5,188,368 to Ryan provides a system for determining in two dimensions which individual square of a chess board a particular chess piece is on during a chess game. The system disclosed by Ryan does not determine the Z direction.
In the case of the surgical tag and detection device, U.S. Pat. No. 6,026,818 to Blair discloses surgical devices, such as sponges, that have activatable resonator tags thereon. A probe with an interrogation ring is provided that can be scanned over an area of a patient after surgery to determine if any surgical devices having the resonator tags have been left behind. Therefore, the detection device of Blair is only detecting the existence or proximity of a surgical tag with the interrogation ring, rather than the actual location of the activatable tags.
In the case of the medical tube placement verification device, U.S. Pat. No. 5,325,873 to Hirschi et al. teaches a system that detects the general position of an object within a body of tissue. The detection system includes a resonant circuit attached to the object and a separate detection probe having a visual display indicating the direction which the probe should be moved to center the detection probe over the object.
The systems of the above patents activate the markers with a pulsed excitation signal generated by driving an untuned source coil with either a unipolar polarity to produce a wide band impulse function or a bipolar polarity to create a waveform that more closely matches the desired resonant frequency of the marker. The required levels of magnetic excitation for the markers in the above patents are relatively low such that the excitation energy in the source coil is substantially consumed after each pulse due to the pulse circuitry resistive losses. The source coils are driven by linear amplifiers, and in one case by linear amplifiers at both ends of the coil, and by a simple pulse network that energizes the coil and extinguishes resistively. The amplitude of the pulsed excitation signal required for these applications is relatively low since either the resonator circuit to be located is of a large size, the volume in which the resonator must be located is relatively small, or the accuracy requirements locating the resonator are quite low. Accordingly, the existing systems are not suitable for use in many situations wherein highly accurate determinations of the marker's location in three-dimensional space are required. The existing systems may also not be suitable for use with efficient, high-energy systems for energizing the marker assemblies so as to provide a sufficient marker signal for use in determining the location of the marker in three-dimensional space relative to remote sensors.
Other systems have been developed for proximity detection of resonator tags for Electronic Article Surveillance (EAS) systems. The requirements for EAS systems are to detect the presence of a security tag within a six-foot wide aisle using one antenna assembly for both excitation and detection of the tag within the aisle. Some EAS systems utilize tuned resonant excitation source coil drive circuitry for pulsed resonator tag operation. As an example, U.S. Pat. No. 5,239,696 to Balch et al. discloses a linear amplifier using current feedback linear power amplifiers to drive an excitation source tuned to resonant coils for use in pulsed EAS systems. The current feedback is used to adjust the linear amplifier's drive current level provided to the tuned excitation source coil load. The current feedback is also used to provide for a relatively constant current drive for exciting resonant EAS tags in the field. The source coil is tuned to allow for use of a simple, low voltage linear amplifier circuit design. The source coil current pulse waveform is determined by the summation of the sinusoidal control signal and the drive current feedback signal input to the linear amplifier.
U.S. Pat. No. 5,640,693 to Balch et al. discloses the use of linear power amplifiers to drive tuned excitation source coils for use in pulsed EAS systems. An apparatus for switching power to a linear amplifier is provided to turn to an “on” state and an “off” state used to control the output drive pulse burst of the tuned excitation source coils. Balch et al. '693 also identifies that linear amplifiers which generate drive signals for a tuned source coil since linear amplifiers are typically only about thirty to forty percent efficient. The inherent inefficiency of the linear amplifier drive is improved by switching the amplifier power “on” and “off” at the same time that the pulse control input signal to the power supply is switched “on” and “off” position.
U.S. Pat. No. 5,815,076 to Herring teaches one of more damping circuits provided in series with excitation source coils and used to promote rapid dampening of the pulsed excitation interrogation signals at the end of each signal pulse. Providing the switchable damping circuits in series with the antenna increases the power dissipation of the device during pulse delivery due to added damping circuit switch resistance in the antenna current path.
The above systems employ a resonator circuit energized with a pulsed excitation signal and the resonator response signal is measured with sensing coils. The amplitude of the pulsed excitation signal required for these applications is relatively low since either the resonator circuit to be located is of a large size, the volume in which the resonator must be located is relatively small, or the accuracy requirements locating the resonator are quite low.
Under one aspect of the invention, a system is provided for generating a pulsed magnetic field for excitation of a leadless marker assembly. The system includes a source generator assembly having a power supply, an energy storage device, a switching network and an untuned source coil interconnected and configured to deliver a pulsed magnetic excitation signal waveform. In one embodiment, the waveform can be configured to contain sufficient energy at the selected leadless marker resonant frequency to energize the marker sufficiently above the ambient environment background noise. The power supply can be configured to deliver power to energize the energy storage device. The switching network can be configured to direct electrical current through the source coil to generate a pulsed magnetic field; alternately switch between a first “on” position and a second “on” position; alternately switch between the first and second “on” positions, switch to an “off” position to prevent energy transfer from the energy storage device to the source coil; alternately transfer stored energy from the energy storage device to the source coil and to transfer stored energy from the source coil back to the energy storage device when switching between the first and second “on” positions; and the untuned source coil being coupled to the switching network to generate a pulsed excitation signal.
Other embodiments of the invention can have other features. Other embodiments are directed toward methods of energizing a leadless marker assembly.
FIG. 1 is a schematic isometric view of a system for pulsing and locating leadless markers in accordance with an embodiment of the present invention.
FIG. 2 is an isometric view of an embodiment of an implantable miniature resonating marker assembly usable in the system of FIG. 1.
FIG. 3 is a schematic block diagram of the pulse excitation system of FIG. 1 illustrating a pulsed generator, a signal processing device, a sensor array, and leadless markers.
FIG. 4 is a schematic block diagram of an embodiment of the pulsed source generator of FIG. 3.
FIG. 5 is a schematic voltage diagram showing the voltage across a source coil of the system of FIG. 1 during excitation “on” and excitation “off” phases over time for the pulsed excitation and location of the marker assembly.
FIG. 6 is a schematic bipolar current diagram during the excitation “on” and excitation “off” phases over time of FIG. 5 for pulsed excitation and location of a marker assembly.
FIG. 7 is a schematic electrical diagram of an alternate embodiment of the system of FIG. 3, the system including a pulse extinguishing circuit.
In the following description, certain specific details are set forth in order to provide a thorough understanding of various embodiments of the invention. However, one skilled in the art will understand that the invention may be practiced without these details. In other instances, well-known structures associated with magnetic excitation systems, resonating markers, and activators have not been shown or described in detail to avoid unnecessarily obscuring the description of the embodiments of the invention.
FIGS. 1-7 illustrate a system and components for generating an excitation signal for activating a resonating marker assembly and locating the marker in three-dimensional space in accordance with embodiments of the present invention. Several of the components described below with reference to FIGS. 1-7 can also be used in systems for performing methods in accordance with aspects of the present invention. Therefore, like reference numbers refer to like components and features throughout the various figures.
FIG. 1 is a schematic isometric view of a system 10 for pulsing and locating one or more leadless resonating marker assemblies 14 in three-dimensional space relative to a sensor array 16 in accordance with one embodiment of the present invention. The system 10 includes a pulsed source generator 18 that generates a pulsed magnetic excitation field or signal 20 that energizes the marker assemblies 14. The energized marker assemblies 14 generate a measurable marker signal 22. In the illustrated embodiment, the marker assemblies 14 are positioned in or on a selected object 24 in a known orientation relative to each other. The marker signals 22 are measured by a plurality of sensors 26 in the sensor array 16. The sensors 26 are coupled to a signal processor 28 that utilizes the measurement of the marker signals 22 from the sensors 26 to calculate the location of each marker assembly 14 in three-dimensional space relative to a known frame of reference, such as the sensor array 16.
In the illustrated embodiment, as discussed in greater detail below, the pulsed source generator 18 is configured to generate the pulsed excitation signal 20 until one or more marker assemblies 14 have been sufficiently energized to generate the marker signals 22 and the pulsed source generator 18 is switched off. Once the pulsed source generator 18 is switched off, the excitation signal 20 terminates and is not measurable. Accordingly, the sensors 26 in the sensor array 16 will receive only the marker signals 22 without any interference or magnetic field distortion induced by the excitation signal 20. Termination of the excitation signal 20 occurs before a measurement phase in which marker signals 22 are measured. Such termination of the excitation signal before the measurement phase when the energized marker assemblies 14 are generating the marker signals 22 allows for a sensor array 16 of increased sensitivity that can provide data of a high signal to noise ratio to the signal processor 28 for extremely accurate determination of the three-dimensional location of the marker assemblies 14 relative to the sensor array or other frame of reference.
The miniature marker assemblies 14 in the system 10 of the illustrated embodiment are inert, activatable assemblies that can be excited to generate a signal at a resonant frequency measurable by the sensor array 16 remote from the target 24. In one embodiment, the miniature marker assemblies 14 have, as one example, a diameter of approximately 2 mm and a length of approximately 5 mm, although other marker assemblies can have different dimensions. An example of the marker detection system is described in detail in co-pending U.S. patent application Ser. No. 09/877,498, titled GUIDED RADIATION THERAPY SYSTEM, filed Jun. 8, 2001, which is incorporated herein in its entirety by reference thereto.
The illustrated marker assembly 14 includes a coil 30 wound around a ferromagnetic core 32 to form an inductor. The inductor is connected to a capacitor 34, so as to form a signal element 36. Accordingly, the signal element 36 is an inductor (L) capacitor (C) resonant circuit. The signal element 36 in one embodiment is enclosed and sealed in an encapsulation member 38 made of plastic, glass, or other inert material. The illustrated marker assembly 14 is a fully contained and inert unit that can be used, as an example, in medical procedures in which the marker assembly is secured on and/or implanted in a patient's body.
Other marker assemblies 14 are described in detail in co-pending U.S. patent application Ser. No. 09/954,700, titled MINIATURE RESONATING MARKER ASSEMBLY, filed Sep. 14, 2001, which is also incorporated herein in its entirety by reference thereto. Other leadless marker assemblies 14 that may be used are described in detail in U.S. patent application Ser. No. 09/078,982, titled SYSTEM AND METHOD FOR BRACKETING AND REMOVING TISSUE, filed May, 14, 1998, now U.S. Pat. No. 6,363,940; PCT Application No. PCT/US00/31667 titled SYSTEMS AND METHODS FOR LOCATING AND DEFINING A TARGET LOCATION WITHIN A HUMAN BODY, filed Nov. 17, 2000; and PCT/US00/31673, titled SYSTEMS AND METHODS FOR STABILIZING A TARGET LOCATION WITHIN A HUMAN BODY, filed Nov. 17, 2000, all of which are incorporated herein in their entireties by reference thereto.
The marker assembly 14 is energized, and thus activated, by the magnetic excitation field or signal 20 generated by the pulsed source generator 18 such that the marker's signal element 36 generates the measurable marker signal 22. The strength of the measurable marker signal 22 is high relative to environmental background noise at the marker resonant frequency, thereby allowing the marker assembly 14 to be precisely located in three-dimensional space relative to the sensor array 16.
The pulsed source generator 18, in one embodiment, is adjustable to generate a pulsed magnetic field 20 having a waveform that contains energy at selected frequencies that substantially match the resonant frequency of the specifically tuned marker assembly 14. When the marker assembly 14 is excited by the magnetic field 20, the signal element 36 generates the response marker signal 22 containing frequency components centered at the marker's resonant frequency. After the marker assembly 14 is energized for a selected time period, the pulsed source generator 18 is switched to the “off” position so the pulsed excitation signal 20 is terminated and provides no measurable interference with the marker signal 22 as received by the sensor array 16.
The marker assembly 14 is constructed to provide an appropriately strong and distinct signal by optimizing marker characteristics and by accurately tuning the marker assembly to a predetermined frequency. Accordingly, multiple uniquely tuned, energized marker assemblies 14 may be reliably and uniquely measured by the sensor array 16. The unique marker assemblies 14 at unique resonant frequencies may be excited and measured simultaneously or during unique time periods. The signal from the tuned miniature marker assembly 14 is significantly above environmental signal noise and sufficiently strong to allow the signal processor 28 (FIG. 1) to determine the marker assembly's identity, precise location, and orientation in three dimensional space relative to the sensor array 16 or other selected reference frame.
The system 10 of the illustrated embodiment in FIG. 1 can be used in many different applications in which the miniature marker's precise three-dimensional location within an accuracy of approximately 1 mm can be uniquely identified within a relatively large navigational volume, such as a volume of 12 cm×12 cm×12 cm or greater. One such application is the use of the system 10 to accurately track the position of targets (e.g., tissue) within the human body. In this application, the leadless marker assemblies 14 are implanted at or near the target so the marker assemblies move with the target as a unit and provide positional references of the target relative to a reference frame outside of the body. Such a system could also track relative positions of therapeutic devices (i.e., surgical tools, tissue ablation devices, radiation delivery devices, or other medical devices) relative to the same fixed reference frame by positioning additional leadless marker assemblies 14 on these devices at known locations or by positioning these devices relative to the reference frame. The size of the leadless markers used on therapeutic devices may be increased to allow for greater marker signal levels and a corresponding increase in navigational volume for these devices.
The system 10 is configured to generate a sufficient source excitation magnetic field signal, as an example, source excitation coil Magnetic Dipole Moment approximately greater than 0.5 A*m2, at the appropriate frequency to energize the one or more marker assemblies significantly above the environmental background noise. The system 10 also generates excitation source magnetic field flux signals at orthogonal spatial orientations (e.g., along the X, Y and Z axes) to excite a marker assembly 14 that may be a resonator having a single coil substantially oriented along a single axis and spatially orthogonal to excitation energy along the other two axes. The system 10 can also be configured to generate excitation source magnetic field flux signals at variable frequencies to energize a plurality of marker assemblies 14 that contain resonant circuits tuned to these unique frequencies. Accordingly, the multiple marker assemblies 14 can be sequentially or simultaneously energized.
The system 10 is also configured to avoid the difficult process of separating the small marker signal 22 from the much more powerful source excitation signal 20 by measuring the marker signal during a time period when the source signal is substantially not present. The residual source excitation signal 20 can cause substantially less accurate results in the location determination if not controlled. The system 10 provides for the measurement of the marker signal 22 with a sufficient number of spatially distributed sensors 26 at a sufficient signal-to-noise ratio so that an inversion algorithm provided in the signal processor 28 can accurately solve for the three-dimensional location of the particular marker assembly 14 relative to the known reference frame of the sensor array 16.
FIG. 3 is a schematic block diagram of the system 10 in accordance with one embodiment. As seen in FIG. 3, the plurality of leadless miniature marker assemblies 14 on the target 24 are remote from the pulsed source generator 18 and from the sensor array 16. The sensor array 16 is operatively coupled to the signal processing device 28.
The pulsed source generator 18 includes a high voltage power supply 40 coupled to an energy storage device 42. In one embodiment, the power supply 40 is a 500-volt power supply, although other power supplies with higher or lower voltages can be used. The energy storage device 42 in one embodiment is a high voltage capacitor that can be charged and maintained at a relatively constant charge by the power supply 40. Energy stored in the storage device 42 allows for providing energy to and removing energy from the source coil inductor. A small amount of stored energy is present in the source coil inductor at maximum current relative to the energy stored in the energy storage device 42.
The energy storage device 42 is capable of storing adequate energy to minimize voltage drop in the energy storage device while having a low series resistance so as to minimize power losses. The energy storage device 42 also has a low series inductance to allow for maximum source generator excitation capability to drive the source coil 46. Specialized aluminum electrolytic capacitors used in flash energy applications may be used in one of the embodiments of system 10. Alternative energy storage devices can also include NiCd and lead acid batteries, as well as alternative capacitor types, such as tantalum, film, or the like.
The pulsed source generator 18 of the illustrated embodiment also includes a switching network 44 coupled between the energy storage device 42 and a plurality of source coils 46. The switching network 44 is configured to control the polarity of the voltage across the source coils 46 and the resultant current magnitude and polarity with time through the source coils so that the source coils 46 each generate the high energy excitation field 20 for activating the marker assemblies (FIG. 1).
In the illustrated embodiment, the excitation source coils 46 includes three coils orthogonally oriented to correspond to the X, Y, and Z axes of a selected frame of reference. The three coils will be referred to herein as the X coil 48, Y coil 50, and Z coil 52, each of which is configured to provide a magnetic field flux signal along the respective X, Y, and Z axes. The X, Y, and Z coils 48, 50, and 52 with their orthogonal orientation effectively avoid blind spots for excitation of marker assemblies 14 and can allow the marker assemblies to be in any orientation relative to the pulsed source generator 18 and still be highly energized upon activation of the excitation source coils 46.
The source coil 46 in the illustrated embodiment is configured to deliver adequate source excitation magnetic fields, which is defined by the area, number of turns, current, and other characteristics of the coil. The source coil 46 is constructed with conductors designed to minimize power loss due to resistive losses as well as resistive losses due to skin effects. Examples include small diameter wire wound in a LITZ wire configuration to minimize skin effects, or alternatively, a thin sheet of conductor to minimize skin effects. Parasitic interwinding capacitance of the source coil inductor and interconnection conductors should also be minimized to reduce unintended coil current spikes due to very short switching network voltage transition times and other unintended source coil resonant circuit effects.
The switching network 44 in the illustrated embodiment includes a plurality of switches that control energy flow to the X, Y, and Z coils 48, 50 and 52 These switches include X-switches 54 coupled to the X-coil 48, Y-switches 56 coupled to the Y-coil 50, and Z-switches 58 coupled to the Z-coil 52. The X-switches 54 include a plurality of activatable switch mechanisms that control the polarity of the voltage across the X-coil 48 so as to control the polarity of the derivative with time of the current flow through the X-coil. The Y-switches 56 control the polarity of the voltage across the Y-coil 50 so as to control the polarity of the derivative with time of the current flow through the Y-coil. Similarly, the Z-switches 58 are configured to control the polarity of the voltage across the Z-coil 52 so as to control the derivative with time of the current flow through the Z-coil. The derivative with time of the current flow at a particular voltage polarity across a particular source coil results in either an increasing or decreasing current ramp with time through the source coil.
In the illustrated embodiment, each of the X, Y, and Z switches 54, 56, and 58 have an H-bridge configuration with four switch mechanisms controlled to selectively direct electrical current through the respective X, Y, or Z coil 48, 50, and 52, thereby generating a pulsed magnetic field from the respective source coil.
The X, Y, and Z switches 50, 56, and 58 are also each configured to alternately switch between first and second “on” positions to generate a current flow with a bipolar waveform. In the first “on” position, the current flow in one has a continually increasing current ramp with time through the respective X, Y, or Z coil 48, 50 or 52 to generate the magnetic excitation field. In the second “on” position, the current flow has a continually decreasing current ramp with time through the respective X, Y, or Z coil 48, 50 or 52 to generate the magnetic excitation field. Such alternate switching over the pulse waveform period effectively provides for alternating the polarity of the current flow from a positive polarity to a negative polarity. The X, Y, and Z switches 54, 56, and 58 are also configured to alternately transfer stored energy from the energy storage device 42 to the respective X, Y, or Z axis source coil 48, 50, or 52 and to transfer the stored energy from the respective source coil back to the energy storage device when alternating switching between the first and second “on” positions.
The X, Y, and Z switches 54, 56, and 58 are also configured to move to an “off” position to prevent energy transfer from the energy storage device 42 to the respective X, Y, or Z coils 48, 50, or 52. Once the X, Y, or Z switch 54, 56, or 58 is switched to the “off” position at the appropriate time when the energy (i.e. the current) in the source coil is substantially zero, the respective X, Y, or Z coil 48, 50, or 52 no longer generates a magnetic field such that the pulsed excitation signal 20 ceases, so only the marker signal 22 emanates from the marker assembly 14 is measurable.
The alternating current flow through the X, Y, or Z coil 48, 50, or 52 generates the pulsed magnetic field in the selected axis to excite the marker assembly 14 located at a determinable distance from the coil. The following is an equation for calculation of the magnetic field excitation at a distance from a source coil inductor of a solenoid shape:
Bmarker(distance)=magnetic field flux density at a distance from the source coil along the coil axis
μo=permeability of free space between the source coil and the marker assembly
rsource=Radius of the source coil (meters)
Nsource=Number of turns of wire around the source coil
Distance=distance from the source coil (meters)
lsource=Electrical current through source coil (amperes)
The electrical current (Isource) through the X, Y, or Z coil 48, 50, or 52 is determined by the voltage applied across the coil inductance (L). The inductance (L) of an air core coil (solenoid) is approximated by:
L=Inductance of the source coil
μo=permeability of free space
rsource=Radius of the source coil (meters)
Nsource=Number of turns of wire around the source coil
lengthsource=Length of source coil (meters)
The inductance of the source coil determines the electrical current derivative with time through source coil inductor as follows:
V=voltage potential across the coil (volts)
L=Inductance of the source coil
dl/dt=The change in coil current with time
To efficiently transfer energy to a coil and create the magnetic excitation field, power losses due to resistance in the source coil circuit should be minimized. The power (i.e., RMS power) in the system is determined as follows:
I=Root Mean Square value of the current
RTOTAL=Total resistance in the source coil circuit
The power losses of the system 10 limits the strength of the magnetic excitation field that the system is capable of delivering. The strength of the magnetic excitation field decreases with the cube of the distance from the magnetic field source (e.g., the source coil 46). Furthermore, the magnetic excitation field increases linearly with current, but the power dissipation in the system increases as the square of the current. Accordingly, the requirements for source drive electronics become more challenging to allow for adequate levels of the marker signal 22 as the magnetic excitation field requirements increase.
In one embodiment, the source coil 46 can be operated as a tuned circuit wherein the source coil inductor is tuned with a capacitor chosen for the desired resonant frequency of the marker assembly 14. The reactance of the inductor is equal to and opposite the capacitor at the frequency of interest, such that only the resistance of the source coil circuit is seen by the drive electronics. Substantial stored energy can occur in the tuned circuit, however, that may limit the time in which the source coil excitation signal is shutoff. Longer shut-off time reduces the time during which the marker resonator signal can be measured effectively in the absence of the source signal. Accordingly, a shorter shutoff time can be very desirable. A shorter shutoff time also allows for adequate marker ring down signal to remain after the source signal has decayed such that the marker signal may be measured at a sufficient signal to noise ratio for accurate location of the marker.
The system 10 of the one embodiment provides an untuned source coil 46 configured to excite the leadless marker assembly's resonator with the pulsed excitation signal 20 having a high level of source excitation energy. The system 10 also provides a very short source excitation turnoff time to achieve optimal performance for measuring the marker signal 22 after the source excitation signal 20 is significantly extinguished. Accordingly, the turnoff time for an untuned source coil can have a significant impact on the effectiveness of the system 10, so the system is configured to have only limited stored energy after turnoff time. Therefore, the pulsed source generator 18 of the system 10 is configured to deliver high source coil current amplitudes at the optimal marker excitation frequencies to energize the leadless markers 14 before the time decaying marker ring down signal is measured.
FIG. 4 is a schematic block diagram of a pulsed source generator 18 of one embodiment. In this illustrated embodiment, a high-voltage power supply 40 and energy storage device 42 are shown coupled to a single switch network 44, which has a single H-bridge switching configuration. This switch network 44 has four switches 62 a-d coupled together so as to control the current flow to a single source coil 64. In this embodiment, when multiple source coils are used, each source coil is coupled to a separate switch network, power supply, and energy storage device. In one embodiment, a common energy storage device and a common power supply for multiple switching networks and corresponding source coils are used.
The switch network 44 of the illustrated embodiment with the H-bridge configuration constructed of MOSFET devices. The switching devices have a low “on” series of resistance (less than or equal to approximately 1 ohm) to minimize power losses. Furthermore, very short switching times (less than approximately 25 nanoseconds) are provided to minimize switching induced power losses and maximum excitation delivery. The short switching times allow for high frequency system operation (for example, 50-600 kHz) that improves overall system performance due to increases in inductive coupling efficiencies between the source, marker, and sensor coils with frequency. Alternate embodiments have switch networks 44 that include one-half H-bridge configurations (having only two switches) with a matched set of power supplies and two matched energy storage devices configured to deliver a bipolar voltage drive to the source coil 46. The alternative switching components can include bipolar junction transistors (BJT), JFETS, and various possible vacuum tube configurations.
The power supply 40 directs charge to and maintains a relatively constant energy storage level at the energy storage device 42 by delivering average power to the energy storage device. The amplitude of the charging current is large enough to compensate for average power consumption in the pulse generator and keep the energy storage device at a relatively constant voltage. The energy storage capacitor must be large enough to minimize voltage drop during pulse generation and capable of both supplying high instantaneous power to the switch network and returning high instantaneous power from the switch network 44. The following example for one embodiment has equations for both calculation of the power supply average power and pulse generator instantaneous power delivery:
Vcap = 500 V
Capacitor charge voltage
Rswitching = 2.0 ohm
Total resistance in “on” state (2
switches closed at a time)
Rcoil = 0.25 ohm
Source coil resistance
Energy storage device resistance
IL(rms) = 4.8 amps
Source coil rms current
Duty cycle = 50%
% of time generator is pulsing
Average power dissipation =
(Rswitching + Rcoil +
* Duty cycle
(2 + 0.25 + 0.05) *
(4.8)2 * 0.5 Watts
Pinstantaneous (during pulsing) =
500 V * 4.8 amps RMS =
2,400 VA RMS
To maintain constant energy storage:
Ipower supply (average)=PPower
The switch network 44 is configured so pairs of the switches 62 a-d are opened and closed simultaneously when the other pair of switches are simultaneously closed and opened. As a result, the switch network 44 is configured to control the voltage across the source coil 64 in alternating polarities. As a result, the current flow through the source coil 64 alternates between positive and negative polarity over the pulsed magnetic excitation signal waveform pulse burst time period. This alternating of the current flow through the source coil between positive and negative polarity results in the pulsed magnetic excitation signal 20 from the source coil.
In one embodiment, the switch network 44 moves between the first “on” position when switches 62 b and 62 c are closed and switches 62 a and 62 d are open, and the second “on” position when switches 62 b and 62 c are open and switches 62 a and 62 d are closed. In this first “on” position, the voltage having a positive direction across the source coil 64 increases the current over the pulse “on” time through the source coil in the direction of arrow 65. In the second “on” position, the voltage having a negative direction across the source coil 64 decreases the current over the pulse “on” time through the source coil in the opposite direction of arrow 65. The resulting pulsed excitation signal due to multiple pulses over the pulse burst time period and the repetition frequency of the pulse burst has determinable frequency components corresponding to the resonant frequencies of the marker assemblies 14 for activation of the markers (not shown).
The switch network 44 also includes an “off” position that opens the circuit to prevent the current from flowing to the source coil. Accordingly, no magnetic field is generated and no pulsed excitation signal 20 is emanated from the source coil 64. The switch network 44 can be switched to the “off” position by opening switches 62 a and 62 b and by turning 62 c and 62 d to a closed position to shunt the source coil which allows for exponential decay of residual energy in the source coil. The current then circulates through one of the two switches 62 c and 62 d and one of two H-bridge protection diodes 67 coupled to the switches depending on the polarity of the residual current. The residual current in the source coil decays by the following exponential time constant:
Lsc=Source coil inductance
RL=Source coil resistance
Rswitch=Switch “on” resistance
As a result, the switch network 44 is controllable to control the pulsed excitation signal 20 and can be switched to the “off” position to terminate the excitation signal after the marker assemblies have been sufficiently energized. When the excitation signal is off, the marker signals 22 do not have to be distinguished from the excitation signal 20 when the marker signal is being measured and analyzed as discussed above.
In an alternate embodiment, the switch network 44 can be switched to the “off” position by opening all switches 62 a-d. However, care must be taken to assure that little residual energy remains in the source coil 64 at the time all switches are turned “off”, otherwise inductive kick back induced voltage spikes due to an instantaneous current change through the inductor with time may damage the switch network or result in undesired oscillations of the residual current in the source coil.
FIG. 5 is a schematic voltage diagram showing the bipolar voltage across a source coil 64 to generate the pulsed excitation signal. The voltage is controlled by activating the switch network 44, as discussed above with respect to FIG. 4. When the switch network 44 is switched to the first “on” position, the voltage across the source coil 64 is positive as shown in FIG. 5 at reference number 66, thereby providing a positive polarity. When the switch network 44 is switched to the second “on” position, the voltage across the source coil 64 shifts and is negative as shown in FIG. 5 at reference number 68, thereby providing a negative polarity.
The switch network 44 (FIG. 4) alternates between the first and second “on” positions so as to alternate the voltage across the source coil 64 between the positive and negative polarities. When the switch network 44 is switched to the first “on” position, energy is drawn from the capacitor 42 toward the source coil 64. When the switch network 44 is switched to the second “on” position, energy is directed back to the capacitor 42 until the time when the current changes polarity and then energy is again drawn from the capacitor. When the switch network 44 is switched back to the first “on” position, then energy is again directed back to the capacitor 42 until the time when the current changes polarity again and then energy is again drawn from the capacitor. As a result, the switching network 44 is configured to alternately transfer stored energy from the energy storage device 42 to the source coil 64 and to transfer the storage energy from the source coil back to the energy storage device when alternately switching between the first and second “on” positions.
In one embodiment, the switch network 44 is configured so that the switches 62 a-d (FIG. 4) are in the first “on” position for the same total time period for a particular pulse burst that they are in the second “on” position. Accordingly, the time period at the positive polarity is the same time period as the negative polarity for the voltage across the source coil 64. When the switch network 44 is switched to the “off” position, the voltage across the source coil 64 is zero, as reflected at reference 70 in the voltage diagram. When the current through the source coil 64 (FIG. 4) is zero, the source coil provides no excitation signal 20 that would interfere with the marker signal 22 generated by the marker assembly 14 as discussed above. Accordingly, the switch network 44 is in the “off” position during the measurement phase when the marker signal 22 is detected and measured for determining the marker assembly's location in three dimensional space.
FIG. 6 is a schematic bipolar current diagram corresponding to the voltage diagram of FIG. 5. Referring to FIGS. 4, 5 and 6, when the switch network 44 (FIG. 4) is in the first “on” position corresponding so the voltage has a positive polarity 66 (FIG. 5), the current flow through the source coil 64 (FIG. 4) has a continually increasing current ramp 70 (FIG. 6) so as to generate the magnetic excitation field 20 with the positive polarity. When the switch network 44 (FIG. 4) is in the second “on” position corresponding to the negative polarity 68 (FIG. 5), the current flow has a continually decreasing current ramp 72 (FIG. 6). When the switch network 44 switches back to the first “on” position, the current flow switches back to an increasing current ramp 70. Accordingly, the current flow has a bipolar, generally non-sinusoidal triangular shaped waveform.
As seen in FIG. 6, when the current flow switches directions, for example from the decreasing current ramp 72 to the increasing current ramp 70, there is a point shown at 74 at which the current in the source coil is substantially at zero amps. Similarly, when the current flow has the decreasing current ramp 72, there is a point shown at 76 at which the current in the source coil 64 (FIG. 4) is at zero amps. The switch network 44 is configured to switch to the “off” position when the current flow through the source coil 64 is substantially at these zero points 74 and 76, and thus at zero amps. When the current in the source coil 64 approaches zero amps, the signal decay time for the pulsed excitation signal 20 approaches zero, such that the pulsed excitation signal is substantially instantaneously shut off so as to provide no interference with the marker signal 22 generated by the energized marker assembly 14.
When the switch network 44 is switched to the “off” position, the extent of signal decay over time of the source coil 64 current is a function of the resistance in the switch network as well as resistance and inductance in the source coil circuitry. In the illustrated embodiment, the switch network 44 and source coil 64 are configured such that when the switch network is switched to the “off” position, any pulsed excitation signal 20 from the source coil is immeasurable within approximately one cycle of the energized marker assembly. Therefore, the sensor array 16 (FIG. 1) and the signal processor 28 are configured to begin measuring the marker signal 22 after one cycle of the marker assemblies 14.
FIG. 7 is a block diagram of a pulsed source generator 90 having a pulse extinguisher circuit 100 therein in accordance with an alternate embodiment. In this alternate embodiment, the pulsed source generator 90 includes the power supply 40 and the energy storage device 42 coupled to the switch network 44 similar to the embodiments discussed above. The switch network 44 is also coupled to the source coil 64. The switch network 44 is also connected to the pulse extinguisher circuit 100 in parallel with the source coil inductor, such that the pulse extinguisher circuit does not conduct current during pulse generation. The pulsed source generator 90 of this alternate embodiment provides the switch network 44 moveable between the first “on” position, the second “on” position as discussed above, and an “off” position where all of the switches, 62 a-62 d, are opened. When the switch network 44 is switched to the “off” position, the pulse extinguisher circuit 100 switches 104 are closed to quickly dissipate the residual energy in the source coil 64 so as to limit the time that an excitation field continues to be generated after the switch network has been moved to the “off” position.
The pulse extinguisher circuit 100 is configured to include a pair of resistors 102 and switches 104 that can be activated to quickly dissipate the residual energy in the source coil when the circuit is closed and to interrupt the current flow through the extinguisher circuit when the switches 104 are open during excitation pulse generation. At the end of a pulse burst, the residual source coil current is conducted through one of the two switches 104, one of the two resistors 102 and an H-bridge protection diode 105, depending on the polarity of the residual current. Pairs of switches 104 and resistors 102 are provided so the residual current may be either of a positive or negative polarity. The time constant for de-energizing the source coil inductor is determined by the following equation:
τ=L sc/(R L +R switch +R protection
Lsc=Source coil inductance
RL=Source coil resistance
Rswitch=Switch “on” resistance
The pulse extinguisher circuit's resistors 102 decrease the exponential decay time constant of residual current in the source coil by adding additional resistance to the source coil circuit only during turnoff time. As a result, the pulse extinguisher circuit 100 decreases the turnoff time of the source generator and does not decrease the overall energy efficiency or power dissipation of the pulsed source generator 90.
In the illustrated embodiment, the pulse extinguisher circuit 100 is configured so that no measurable or detectable excitation field remains after the switch network 44 has been moved to the “off” position within less than one cycle of the resonating marker assembly 14 (FIG. 1). Accordingly, the pulse extinguisher circuit 100 facilitates the termination of the pulsed excitation signal 20 so that the resonating marker assembly 14 can be easily detectable and located with the signal processing assembly 28 to accurately identify the three-dimensional location of the resonating marker assembly relative to the sensor array 16.
While the pulse extinguisher circuit 100 is defined in the illustrated embodiment as providing the resistors 102 and switches 104, with additional protection diodes 105, other pulse extinguisher circuits can be used so as to increase the resistance of the total source coil circuit when the switch network is in the “off” position. The alternate pulse extinguisher circuits should not increase system power dissipation and decrease energy efficiency by adding additional switch resistance during pulse delivery because of its presence.
Although specific embodiments of, and examples for, the present invention are described herein for illustrative purposes, various equivalent modifications can be made without departing from the spirit and scope of the invention, as will be recognized by those skilled in the relevant art. The teachings provided herein of the present invention can be applied to systems for excitation of leadless miniature markers, not necessarily the exemplary system generally described above.
From the foregoing it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention. Accordingly, the invention is not limited except as by the appended claims.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US3752960||27 Dec 1971||14 Aug 1973||C Walton||Electronic identification & recognition system|
|US3967161||19 Jul 1974||29 Jun 1976||Lichtblau G J||A multi-frequency resonant tag circuit for use with an electronic security system having improved noise discrimination|
|US4017858||24 Feb 1975||12 Apr 1977||Polhemus Navigation Sciences, Inc.||Apparatus for generating a nutating electromagnetic field|
|US4023167||16 Jun 1975||10 May 1977||Wahlstrom Sven E||Radio frequency detection system and method for passive resonance circuits|
|US4123749||28 Mar 1977||31 Oct 1978||Bizerba-Werke Wilhelm Kraut Kg||Method and system for determining the presence of objects within a particular surveillance area, in particular for prevention of shoplifting|
|US4160971||29 Apr 1976||10 Jul 1979||National Research Development Corporation||Transponders|
|US4260990||8 Nov 1979||7 Apr 1981||Lichtblau G J||Asymmetrical antennas for use in electronic security systems|
|US4466075||23 Nov 1981||14 Aug 1984||Siemens Gammasonics, Inc.||Motion correction circuitry and method for a radiation imaging device|
|US4633250||7 Jan 1985||30 Dec 1986||Allied Corporation||Coplanar antenna for proximate surveillance systems|
|US4642786||25 May 1984||10 Feb 1987||Position Orientation Systems, Ltd.||Method and apparatus for position and orientation measurement using a magnetic field and retransmission|
|US4737794||9 Dec 1985||12 Apr 1988||Mcdonnell Douglas Corporation||Method and apparatus for determining remote object orientation and position|
|US4795995||22 Sep 1986||3 Jan 1989||Progressive Dynamics, Inc.||Method and apparatus for producing electromagnetic surveillance fields|
|US4849692||9 Oct 1986||18 Jul 1989||Ascension Technology Corporation||Device for quantitatively measuring the relative position and orientation of two bodies in the presence of metals utilizing direct current magnetic fields|
|US4945305||11 Apr 1989||31 Jul 1990||Ascension Technology Corporation||Device for quantitatively measuring the relative position and orientation of two bodies in the presence of metals utilizing direct current magnetic fields|
|US5050608||4 Sep 1990||24 Sep 1991||Medirand, Inc.||System for indicating a position to be operated in a patient's body|
|US5095224 *||31 Aug 1990||10 Mar 1992||Siemens-Pacesetter, Inc.||Interrupted resonance energy transfer system|
|US5099845||23 May 1990||31 Mar 1992||Micronix Pty Ltd.||Medical instrument location means|
|US5142292||5 Aug 1991||25 Aug 1992||Checkpoint Systems, Inc.||Coplanar multiple loop antenna for electronic article surveillance systems|
|US5188368||25 Oct 1990||23 Feb 1993||Saitek Limited||Electronic game apparatus|
|US5198877||15 Oct 1990||30 Mar 1993||Pixsys, Inc.||Method and apparatus for three-dimensional non-contact shape sensing|
|US5221269||15 Oct 1990||22 Jun 1993||Cook Incorporated||Guide for localizing a nonpalpable breast lesion|
|US5240011||27 Nov 1991||31 Aug 1993||Fischer Imaging Corporation||Motorized biopsy needle positioner|
|US5325873||23 Jul 1992||5 Jul 1994||Abbott Laboratories||Tube placement verifier system|
|US5377678||14 Jul 1993||3 Jan 1995||General Electric Company||Tracking system to follow the position and orientation of a device with radiofrequency fields|
|US5397329||26 Feb 1993||14 Mar 1995||Allen; George S.||Fiducial implant and system of such implants|
|US5411026||8 Oct 1993||2 May 1995||Nomos Corporation||Method and apparatus for lesion position verification|
|US5417210||27 May 1992||23 May 1995||International Business Machines Corporation||System and method for augmentation of endoscopic surgery|
|US5425382||14 Sep 1993||20 Jun 1995||University Of Washington||Apparatus and method for locating a medical tube in the body of a patient|
|US5446548||8 Oct 1993||29 Aug 1995||Siemens Medical Systems, Inc.||Patient positioning and monitoring system|
|US5453686||8 Apr 1993||26 Sep 1995||Polhemus Incorporated||Pulsed-DC position and orientation measurement system|
|US5515853||28 Mar 1995||14 May 1996||Sonometrics Corporation||Three-dimensional digital ultrasound tracking system|
|US5526812||27 Oct 1995||18 Jun 1996||General Electric Company||Display system for enhancing visualization of body structures during medical procedures|
|US5528651||9 Jun 1994||18 Jun 1996||Elekta Instrument Ab||Positioning device and method for radiation treatment|
|US5546951||23 Sep 1994||20 Aug 1996||Biosense, Inc.||Method and apparatus for studying cardiac arrhythmias|
|US5558091||6 Oct 1993||24 Sep 1996||Biosense, Inc.||Magnetic determination of position and orientation|
|US5568809||12 Jul 1995||29 Oct 1996||Biosense, Inc.||Apparatus and method for intrabody mapping|
|US5572999||26 Jan 1995||12 Nov 1996||International Business Machines Corporation||Robotic system for positioning a surgical instrument relative to a patient's body|
|US5617857||6 Jun 1995||8 Apr 1997||Image Guided Technologies, Inc.||Imaging system having interactive medical instruments and methods|
|US5622170||4 Oct 1994||22 Apr 1997||Image Guided Technologies, Inc.||Apparatus for determining the position and orientation of an invasive portion of a probe inside a three-dimensional body|
|US5622187||30 Sep 1994||22 Apr 1997||Nomos Corporation||Method and apparatus for patient positioning for radiation therapy|
|US5629967||13 Feb 1996||13 May 1997||Elekta Instrument Ab||Positioning device and method for radiation treatment|
|US5630431||11 Oct 1994||20 May 1997||International Business Machines Corporation||System and method for augmentation of surgery|
|US5645065||11 Apr 1995||8 Jul 1997||Navion Biomedical Corporation||Catheter depth, position and orientation location system|
|US5680106||27 Oct 1995||21 Oct 1997||International Business Machines Corporation||Multibit tag with stepwise variable frequencies|
|US5681326||13 Jun 1994||28 Oct 1997||Elekta Instrument Ab||Stereotactical instrument|
|US5727552||11 Jan 1996||17 Mar 1998||Medtronic, Inc.||Catheter and electrical lead location system|
|US5745545||16 Aug 1996||28 Apr 1998||Siemens Medical Systems, Inc.||Alignment system and method for intra-operative radiation therapy|
|US5764052 *||16 Jun 1995||9 Jun 1998||Pacesetter, Inc.||Coil return energy measurement magnetic field sensor and method thereof|
|US5779638||17 Apr 1997||14 Jul 1998||Sonometrics Corporation||Ultrasound-based 3-D tracking system using a digital signal processor|
|US5797849||7 Mar 1997||25 Aug 1998||Sonometrics Corporation||Method for carrying out a medical procedure using a three-dimensional tracking and imaging system|
|US5805661||8 Jan 1997||8 Sep 1998||Elekta Instrument Ab||Positioning device and method for radiation treatment|
|US5815076 *||16 Jan 1996||29 Sep 1998||Sensormatic Electronics Corporation||Pulsed-signal magnetomechanical electronic article surveillance system with improved damping of transmitting antenna|
|US5817022||11 Mar 1997||6 Oct 1998||Sonometrics Corporation||System for displaying a 2-D ultrasound image within a 3-D viewing environment|
|US5820553||16 Aug 1996||13 Oct 1998||Siemens Medical Systems, Inc.||Identification system and method for radiation therapy|
|US5823192||31 Jul 1996||20 Oct 1998||University Of Pittsburgh Of The Commonwealth System Of Higher Education||Apparatus for automatically positioning a patient for treatment/diagnoses|
|US5828770||20 Feb 1996||27 Oct 1998||Northern Digital Inc.||System for determining the spatial position and angular orientation of an object|
|US5830144||6 Mar 1997||3 Nov 1998||Vesely; Ivan||Tracking data sheath|
|US5868673||11 Mar 1997||9 Feb 1999||Sonometrics Corporation||System for carrying out surgery, biopsy and ablation of a tumor or other physical anomaly|
|US5868675||10 May 1990||9 Feb 1999||Elekta Igs S.A.||Interactive system for local intervention inside a nonhumogeneous structure|
|US5879357||10 Sep 1997||9 Mar 1999||United States Surgical Corporation||Apparatus for marking tissue location|
|US5902238||2 May 1996||11 May 1999||University Of Washington||Medical tube and apparatus for locating the same in the body of a patient|
|US5902310||21 Feb 1997||11 May 1999||Ethicon Endo-Surgery, Inc.||Apparatus and method for marking tissue|
|US5913820||16 Aug 1993||22 Jun 1999||British Telecommunications Public Limited Company||Position location system|
|US5923417||26 Sep 1997||13 Jul 1999||Northern Digital Incorporated||System for determining the spatial position of a target|
|US5987349||18 Apr 1997||16 Nov 1999||Image Guided Technologies, Inc.||Method for determining the position and orientation of two moveable objects in three-dimensional space|
|US6015390||12 Jun 1998||18 Jan 2000||D. Krag Llc||System and method for stabilizing and removing tissue|
|US6019725||7 Mar 1997||1 Feb 2000||Sonometrics Corporation||Three-dimensional tracking and imaging system|
|US6026818||2 Mar 1998||22 Feb 2000||Blair Port Ltd.||Tag and detection device|
|US6049587||8 Oct 1997||11 Apr 2000||Elekta Instruments Ab||Positioning device and method for radiation treatment|
|US6052477||6 Jul 1998||18 Apr 2000||George S. Allen||Automatic technique for localizing externally attached fiducial markers in volume images of the head|
|US6061644||5 Dec 1997||9 May 2000||Northern Digital Incorporated||System for determining the spatial position and orientation of a body|
|US6064904||28 Nov 1997||16 May 2000||Picker International, Inc.||Frameless stereotactic CT scanner with virtual needle display for planning image guided interventional procedures|
|US6067465||26 Nov 1997||23 May 2000||General Electric Company||System and method for detecting and tracking reference position changes with linear phase shift in magnetic resonance imaging|
|US6094007||17 Jul 1998||25 Jul 2000||Image Guided Technologies, Inc.||Optical tracking system|
|US6097994||30 Sep 1996||1 Aug 2000||Siemens Corporate Research, Inc.||Apparatus and method for determining the correct insertion depth for a biopsy needle|
|US6144875||16 Mar 1999||7 Nov 2000||Accuray Incorporated||Apparatus and method for compensating for respiratory and patient motion during treatment|
|US6173715||1 Mar 1999||16 Jan 2001||Lucent Medical Systems, Inc.||Magnetic anatomical marker and method of use|
|US6198963||14 May 1998||6 Mar 2001||Biosense, Inc.||Position confirmation with learn and test functions|
|US6239724||21 May 1999||29 May 2001||Remon Medical Technologies, Ltd.||System and method for telemetrically providing intrabody spatial position|
|US6363940||14 May 1998||2 Apr 2002||Calypso Medical Technologies, Inc.||System and method for bracketing and removing tissue|
|US6371379||16 Feb 1996||16 Apr 2002||Flying Null Limited||Magnetic tags or markers|
|US6401722||18 Nov 1999||11 Jun 2002||Calypso Medical Technologies, Inc.||Method for stabilizing and removing tissue|
|US6474341||28 Oct 1999||5 Nov 2002||Surgical Navigation Technologies, Inc.||Surgical communication and power system|
|US20030088178 *||2 Nov 2001||8 May 2003||Owens Timothy R||Method and apparatus for computer modified magnetic resonance imaging|
|USRE35816||30 Mar 1995||2 Jun 1998||Image Guided Technologies Inc.||Method and apparatus for three-dimensional non-contact shape sensing|
|EP0719420B1||14 Sep 1994||24 Nov 1999||University of Washington||Apparatus and method for locating a medical tube in the body of a patient|
|EP1034738A1||10 Mar 2000||13 Sep 2000||Biosense, Inc.||Position sensing based on ultrasound emission|
|WO1988008282A1||27 Apr 1988||3 Nov 1988||Elekta Instrument Ab||Apparatus for marking an operating site|
|WO1995033519A1||9 Jun 1995||14 Dec 1995||Elekta Instrument Ab||Positioning device and method for radiation treatment|
|WO1996008208A1||12 Sep 1995||21 Mar 1996||Biopsys Medical, Inc.||Methods and devices for defining and marking tissue|
|WO1996008999A1||22 Sep 1995||28 Mar 1996||Lennernaes Bo||Use of implant with magnetic properties to determine the position of a patient|
|WO1997036192A1||27 Mar 1997||2 Oct 1997||Paul Scherrer Institut||Device and process for determining position|
|WO1997048438A2||13 Jun 1997||24 Dec 1997||Lucent Medical Systems, Inc.||Medical tube for insertion and detection within the body of a patient|
|WO1998030166A1||8 Jan 1998||16 Jul 1998||Fabian Carl E||Surgical implement detector utilizing a smart marker|
|WO1999017133A1||28 Sep 1998||8 Apr 1999||Northern Digital Incorporated||A system for determining the spatial position of a target|
|WO1999027839A2||1 Dec 1998||10 Jun 1999||Cosman Eric R||Surgical positioning system|
|WO1999030182A1||2 Dec 1998||17 Jun 1999||Northern Digital Inc.||A system for determining the spatial position and orientation of a body|
|WO1999035966A1||6 Jan 1999||22 Jul 1999||Leonard Reiffel||System to stabilize an irradiated internal target|
|WO1999058055A1||7 May 1999||18 Nov 1999||Sonometrics Corporation||A method for carrying out a medical procedure using a three-dimensional tracking and imaging system|
|WO1999058065A1||14 May 1999||18 Nov 1999||Krag, David, N.||System and method for bracketing and removing tissue|
|WO2000024332A1||20 Oct 1999||4 May 2000||Cortese Armand F||Marker for indicating the location of identified tissue|
|WO2000051514A1||29 Feb 2000||8 Sep 2000||Lucent Medical Systems, Inc.||Magnetic anatomical marker and method of use|
|WO2001034049A2||26 Oct 2000||17 May 2001||Medtronic Surgical Navigation Technologies||Surgical communication and power system|
|WO2001054765A2||30 Jan 2001||2 Aug 2001||Zmed, Incorporated||Method and apparatus for alignment of medical radiation beams using a body frame|
|WO2002019908A1||6 Sep 2001||14 Mar 2002||Accuray Incorporated||Apparatus and method for compensating for respiratory and patient motion during treatment|
|1||Hsiao, K., "Fast Multi-Axis Tracking of Magnetically-Resonant Passive Tags: Methods and Applications," Feb. 2001, Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science.|
|2||International Search Report dated Jan. 24, 2003, PCT Application No. PCT/US/29390.|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US6906528 *||30 Sep 2003||14 Jun 2005||The Regents Of The University Of California||Electronic non-contacting linear position measuring system|
|US6977504 *||31 Dec 2003||20 Dec 2005||Calypso Medical Technologies, Inc.||Receiver used in marker localization sensing system using coherent detection|
|US7194303 *||3 Feb 2005||20 Mar 2007||Cameron Health, Inc.||H-bridge with sensing circuit|
|US7464713 *||26 Nov 2003||16 Dec 2008||Fabian Carl E||Miniature magnetomechanical tag for detecting surgical sponges and implements|
|US7561051||18 Apr 2006||14 Jul 2009||Creare Inc.||Magnet locating apparatus and method of locating a magnet using such apparatus|
|US7676268||30 Nov 2006||9 Mar 2010||Medtronic, Inc.||Medical methods and systems incorporating wireless monitoring|
|US7684849 *||31 Dec 2003||23 Mar 2010||Calypso Medical Technologies, Inc.||Marker localization sensing system synchronized with radiation source|
|US7696877||1 May 2007||13 Apr 2010||Rf Surgical Systems, Inc.||Method, apparatus and article for detection of transponder tagged objects, for example during surgery|
|US7769445||27 Feb 2007||3 Aug 2010||Cameron Health, Inc.||Implantable cardioverter-defibrillator with post-shock reset|
|US7778687||23 Dec 2003||17 Aug 2010||Calypso Medical Technologies, Inc.||Implantable marker with a leadless signal transmitter compatible for use in magnetic resonance devices|
|US7847274||11 Aug 2005||7 Dec 2010||Navotek Medical Ltd.||Localization of a radioactive source within a body of a subject|
|US7899513||25 Jul 2005||1 Mar 2011||Calypso Medical Technologies, Inc.||Modular software system for guided radiation therapy|
|US7912529||30 Dec 2002||22 Mar 2011||Calypso Medical Technologies, Inc.||Panel-type sensor/source array assembly|
|US7926491||4 Mar 2003||19 Apr 2011||Calypso Medical Technologies, Inc.||Method and apparatus for sensing field strength signals to estimate location of a wireless implantable marker|
|US7942843||16 Jul 2009||17 May 2011||Navotek Medical Ltd.||Implantation device for soft tissue markers and other implants|
|US7952079||10 Aug 2006||31 May 2011||Navotek Medical Ltd.||Localization of a radioactive source|
|US8010183 *||25 Mar 2008||30 Aug 2011||Olympus Corporation||Detecting system of position and posture of capsule medical device|
|US8095203||25 Jul 2005||10 Jan 2012||Varian Medical Systems, Inc.||Data processing for real-time tracking of a target in radiation therapy|
|US8111162||27 May 2009||7 Feb 2012||Rf Surgical Systems, Inc.||Method, apparatus and article for detection of transponder tagged objects, for example during surgery|
|US8164064||18 Nov 2010||24 Apr 2012||Navotek Medical Ltd.||Localization of a radioactive source within a body of a subject|
|US8173446||21 Dec 2009||8 May 2012||General Electric Company||Method of producing an integrated micromagnet sensor assembly|
|US8174366||13 Aug 2007||8 May 2012||Veroscan, Inc.||Interrogator and interrogation system employing the same|
|US8196589||24 Dec 2003||12 Jun 2012||Calypso Medical Technologies, Inc.||Implantable marker with wireless signal transmitter|
|US8198588||1 Nov 2010||12 Jun 2012||Navotek Medical Ltd.||Localization of a radioactive source within a body of a subject|
|US8198600||21 Apr 2011||12 Jun 2012||Navotek Medical Ltd.||Localization of a radioactive source|
|US8239002||10 Aug 2006||7 Aug 2012||Novatek Medical Ltd.||Guiding a tool for medical treatment by detecting a source of radioactivity|
|US8239005||8 Jan 2010||7 Aug 2012||Varian Medical Systems, Inc.||Systems and methods for real-time tracking of targets in radiation therapy and other medical applications|
|US8244330||25 Jul 2005||14 Aug 2012||Varian Medical Systems, Inc.||Integrated radiation therapy systems and methods for treating a target in a patient|
|US8264342||27 Oct 2009||11 Sep 2012||RF Surgical Systems, Inc||Method and apparatus to detect transponder tagged objects, for example during medical procedures|
|US8283921||26 Nov 2008||9 Oct 2012||General Electric Company||Magnetoresistance sensors for position and orientation determination|
|US8340742||25 Jul 2005||25 Dec 2012||Varian Medical Systems, Inc.||Integrated radiation therapy systems and methods for treating a target in a patient|
|US8358128||28 Nov 2008||22 Jan 2013||General Electric Company||Surgical navigation system with magnetoresistance sensors|
|US8358212||26 May 2009||22 Jan 2013||Rf Surgical Systems, Inc.||Multi-modal transponder and method and apparatus to detect same|
|US8391952||11 Oct 2007||5 Mar 2013||General Electric Company||Coil arrangement for an electromagnetic tracking system|
|US8437449||25 Jul 2005||7 May 2013||Varian Medical Systems, Inc.||Dynamic/adaptive treatment planning for radiation therapy|
|US8452375||23 Dec 2003||28 May 2013||Varian Medical Systems, Inc.||Systems and methods for locating and defining a target location within a human body|
|US8473030||12 Jan 2007||25 Jun 2013||Medtronic Vascular, Inc.||Vessel position and configuration imaging apparatus and methods|
|US8483800||29 Nov 2008||9 Jul 2013||General Electric Company||Surgical navigation enabled imaging table environment|
|US8542717||13 Aug 2007||24 Sep 2013||Veroscan, Inc.||Interrogator and interrogation system employing the same|
|US8552869 *||2 May 2007||8 Oct 2013||Veroscan, Inc.||Interrogator and interrogation system employing the same|
|US8692682 *||28 Sep 2007||8 Apr 2014||Olympus Medical Systems Corp.||Position detection system for detection object and position detection method for detection object|
|US8710957||27 Feb 2008||29 Apr 2014||Rf Surgical Systems, Inc.||Method, apparatus and article for detection of transponder tagged objects, for example during surgery|
|US8726911||27 Oct 2009||20 May 2014||Rf Surgical Systems, Inc.||Wirelessly detectable objects for use in medical procedures and methods of making same|
|US8831720||25 Oct 2013||9 Sep 2014||Cameron Health, Inc.||Method of implanting and using a subcutaneous defibrillator|
|US8857043||27 Sep 2007||14 Oct 2014||Varian Medical Systems, Inc.||Method of manufacturing an implantable marker with a leadless signal transmitter|
|US8878668||2 May 2012||4 Nov 2014||Rf Surgical Systems, Inc.||Method and apparatus to detect transponder tagged objects, for example during medical procedures|
|US8917086||19 Jul 2011||23 Dec 2014||Lawrence Livermore National Security, Llc||Position sensor for linear synchronous motors employing halbach arrays|
|US8948279||3 Mar 2005||3 Feb 2015||Veroscan, Inc.||Interrogator and interrogation system employing the same|
|US9035774||10 Apr 2012||19 May 2015||Lone Star Ip Holdings, Lp||Interrogator and system employing the same|
|US9050235||2 May 2012||9 Jun 2015||Rf Surgical Systems, Inc.||Method and apparatus to detect transponder tagged objects, for example during medical procedures|
|US9072895||27 Sep 2010||7 Jul 2015||Varian Medical Systems, Inc.||Guided radiation therapy system|
|US9135669||2 Mar 2009||15 Sep 2015||Lone Star Ip Holdings, Lp||Interrogation system employing prior knowledge about an object to discern an identity thereof|
|US9138589||4 Apr 2014||22 Sep 2015||Cameron Health, Inc.||Apparatus and method for identifying atrial arrhythmia by far-field sensing|
|US9168083||10 Aug 2009||27 Oct 2015||Erbe Elektromedizin Gmbh||HR surgical generator|
|US9226686||22 Nov 2010||5 Jan 2016||Rf Surgical Systems, Inc.||Method and apparatus to account for transponder tagged objects used during medical procedures|
|US9237860||5 Jun 2009||19 Jan 2016||Varian Medical Systems, Inc.||Motion compensation for medical imaging and associated systems and methods|
|US9238151||6 May 2013||19 Jan 2016||Varian Medical Systems, Inc.||Dynamic/adaptive treatment planning for radiation therapy|
|US9248003 *||31 Dec 2003||2 Feb 2016||Varian Medical Systems, Inc.||Receiver used in marker localization sensing system and tunable to marker frequency|
|US9470787||13 May 2015||18 Oct 2016||Lone Star Ip Holdings, Lp||Interrogator and system employing the same|
|US9514341||9 Jul 2014||6 Dec 2016||Covidien Lp|
|US9522283||27 Aug 2015||20 Dec 2016||Cameron Health Inc.||Apparatus and method for identifying atrial arrhythmia by far-field sensing|
|US9586059||25 Jul 2005||7 Mar 2017||Varian Medical Systems, Inc.||User interface for guided radiation therapy|
|US9616248||26 Jul 2012||11 Apr 2017||Varian Medical Systems, Inc.||Integrated radiation therapy systems and methods for treating a target in a patient|
|US9623208||12 Jan 2005||18 Apr 2017||Varian Medical Systems, Inc.||Instruments with location markers and methods for tracking instruments through anatomical passageways|
|US9682253||25 Jul 2005||20 Jun 2017||Varian Medical Systems, Inc.||Integrated radiation therapy systems and methods for treating a target in a patient|
|US9690963||24 Feb 2016||27 Jun 2017||Covidien Lp||Hand-held dual spherical antenna system|
|US9717565||21 Jan 2016||1 Aug 2017||Covidien Lp||Wirelessly detectable objects for use in medical procedures and methods of making same|
|US9730764||11 Jan 2016||15 Aug 2017||Elucent Medical, Inc.||Signal tag detection components, devices, and systems|
|US9730850||3 Nov 2014||15 Aug 2017||Covidien Lp||Method and apparatus to detect transponder tagged objects, for example during medical procedures|
|US9763742||8 Apr 2014||19 Sep 2017||Covidien Lp||Wirelessly detectable objects for use in medical procedures and methods of making same|
|US9814540||10 Nov 2016||14 Nov 2017||Covidien Lp|
|US20010018594 *||22 Mar 2001||30 Aug 2001||Calypso Medical, Inc.||System and Method for Bracketing and Removing Tissue|
|US20040129279 *||26 Nov 2003||8 Jul 2004||Fabian Carl E.||Miniature magnetomechanical tag for detecting surgical sponges and implements|
|US20050068042 *||30 Sep 2003||31 Mar 2005||The Regents Of The University Of California||Electronic non-contacting linear position measuring system|
|US20050131466 *||3 Feb 2005||16 Jun 2005||Cameron Health, Inc.||H-bridge with sensing circuit|
|US20050140372 *||31 Dec 2003||30 Jun 2005||Wright J. N.||Receiver used in marker localization sensing system using coherent detection|
|US20060276680 *||16 Aug 2006||7 Dec 2006||Calypso Medical Technologies, Inc.||Apparatuses and methods for percutaneously implanting objects in patients|
|US20070055090 *||10 Aug 2006||8 Mar 2007||Navotek Medical Ltd.||Medical Treatment System and Method|
|US20070179537 *||27 Feb 2007||2 Aug 2007||Cameron Health, Inc.||Implantable Cardioverter-Defibrillator With Post-Shock Reset|
|US20070205373 *||11 Aug 2005||6 Sep 2007||Navotek Medical Ltd.||Localization of a Radioactive Source Within a Body of a Subject|
|US20070225596 *||3 May 2005||27 Sep 2007||Micropos Medical Ab||Implant, Apparatus and Method for Tracking a Target Area|
|US20070285249 *||6 Jun 2007||13 Dec 2007||Rf Surgical Systems, Inc.|
|US20080132800 *||30 Nov 2006||5 Jun 2008||Hettrick Douglas A||Novel medical methods and systems incorporating wireless monitoring|
|US20080139915 *||2 Apr 2007||12 Jun 2008||Medtronic Vascular, Inc.||Vascular Position Locating and/or Mapping Apparatus and Methods|
|US20080140180 *||7 Dec 2006||12 Jun 2008||Medtronic Vascular, Inc.||Vascular Position Locating Apparatus and Method|
|US20080147173 *||18 Dec 2006||19 Jun 2008||Medtronic Vascular, Inc.||Prosthesis Deployment Apparatus and Methods|
|US20080171934 *||12 Jan 2007||17 Jul 2008||Medtronic Vascular, Inc.||Vessel Position and Configuration Imaging Apparatus and Methods|
|US20080172119 *||12 Jan 2007||17 Jul 2008||Medtronic Vascular, Inc.||Prosthesis Deployment Apparatus and Methods|
|US20080188921 *||2 Feb 2007||7 Aug 2008||Medtronic Vascular, Inc.||Prosthesis Deployment Apparatus and Methods|
|US20080262473 *||19 Oct 2005||23 Oct 2008||Navotek Medical Ltd.||Locating a Catheter Tip Using a Tracked Guide|
|US20080281188 *||25 Mar 2008||13 Nov 2008||Olympus Corporation||Detecting system of position and posture of capsule medical device|
|US20090096443 *||11 Oct 2007||16 Apr 2009||General Electric Company||Coil arrangement for an electromagnetic tracking system|
|US20090127459 *||10 Aug 2006||21 May 2009||Navotek Medical Ltd.||Localization of a Radioactive Source|
|US20090131734 *||15 Feb 2007||21 May 2009||Navotek Medical Ltd.||Implantable medical marker and methods of preparation thereof|
|US20090209804 *||25 Jul 2005||20 Aug 2009||Calypso Medical Technologies, Inc.||Apparatuses and methods for percutaneously implanting objects in patients|
|US20090259284 *||10 Apr 2008||15 Oct 2009||Medtronic Vascular, Inc.||Resonating Stent or Stent Element|
|US20090322485 *||27 May 2009||31 Dec 2009||Barnes Bruce E|
|US20100042041 *||16 Jul 2009||18 Feb 2010||Navotek Medical Ltd.||Implantation device for soft tissue markers and other implants|
|US20100060472 *||28 Sep 2007||11 Mar 2010||Olympus Medical Systems Corp.||Position detection system for detection object and position detection method for detection object|
|US20100127696 *||26 Nov 2008||27 May 2010||General Electric Company||Magnetoresistance sensors for position and orientation determination|
|US20100137705 *||28 Nov 2008||3 Jun 2010||General Electric Company||Surgical Navigation System with Magnetoresistance Sensors|
|US20100138183 *||29 Nov 2008||3 Jun 2010||General Electric Company||Surgical Navigation Enabled Imaging Table Environment|
|US20100249571 *||31 Mar 2009||30 Sep 2010||General Electric Company||Surgical navigation system with wireless magnetoresistance tracking sensors|
|US20100305427 *||1 Jun 2009||2 Dec 2010||General Electric Company||Long-range planar sensor array for use in a surgical navigation system|
|US20110009736 *||9 Jul 2009||13 Jan 2011||Maltz Jonathan S||Localization Using Non-Metallic Implantable Fiducial Markers|
|US20110151587 *||21 Dec 2009||23 Jun 2011||General Electric Company||Method of producing an integrated micromagnet sensor assembly|
|US20110170321 *||10 Aug 2009||14 Jul 2011||Heiko Schall||Hf surgical generator|
|USD775331||2 Mar 2015||27 Dec 2016||Covidien Lp||Hand-held antenna system|
|EP1943974A1||14 Jan 2008||16 Jul 2008||Medtronic Vascular, Inc.||Vessel position and configuration imaging apparatus and methods|
|EP1943988A1||14 Jan 2008||16 Jul 2008||Medtronic Vascular, Inc.||Prosthesis deployment apparatus and methods|
|EP2070489A1||18 Dec 2007||17 Jun 2009||Medtronic Vascular, Inc.||Bifurcated prosthesis comprising electromagnetic markers|
|EP2272456A1||29 Apr 2010||12 Jan 2011||Siemens Aktiengesellschaft||Localization using non-metallic implantable fiducial markers|
|WO2004061460A3 *||24 Dec 2003||7 Jul 2005||Calypso Med Technologies Inc||Implantable marker with a wireless signal transmitter compatible for use in magnetic resonance imaging devices and/or suitable for use in radiation imaging processes|
|U.S. Classification||340/572.4, 340/573.1, 340/572.5|
|International Classification||G01S5/16, G01B7/00, A61N5/10, A61B19/00|
|Cooperative Classification||G01B7/003, A61B34/20, A61B90/36, A61B2017/00411, A61N2005/1051, A61N5/1049, A61B2090/3975, A61B2034/2051, A61B2090/3958|
|European Classification||A61B19/52H12, A61B19/52|
|6 Feb 2002||AS||Assignment|
Owner name: CALYPSO MEDICAL, INC., WASHINGTON
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:DIMMER, STEVEN C.;REEL/FRAME:012589/0469
Effective date: 20020111
|1 May 2005||AS||Assignment|
Owner name: CALYPSO MEDICAL TECHNOLOGIES, INC., WASHINGTON
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:DIMMER, STEVEN C.;REEL/FRAME:015962/0319
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|14 Nov 2011||AS||Assignment|
Owner name: VARIAN MEDICAL SYSTEMS, INC., CALIFORNIA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:CALYPSO MEDICAL TECHNOLOGIES, INC.;REEL/FRAME:027221/0245
Effective date: 20111111
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